The bodylink seat may well be more forgiving (mine's the older one-piece version, on which there is exactly one really comfortable stable position), and I think you're right that a more reclined seat is less critical of leg-length. I successfully managed to ride Charlotte's Optima Baron, in spite of the boom being about 6" too long for me, thanks to the relatively reclined position (it wasn't especially comfortable, though, and I had trouble seeing over the bars).
I don't know about anyone else, but I find that recumbents benefit from a more ankly pedalling technique than DF bikes, which gives a little bit more flexibility to compensate for boom adjustment.
...and of course if you havent' played with it, there's always the possibility that there's a better position you simply haven't discovered yet 
If it wasn't for my dodgy knees I'd be inclined to agree - on a DF I have my seatpost a lot higher than most, relatively, and then tend to sit on the back of the seat too (so much for KOPS !), and even with the USE shockpost that's on one mtb I can still discern a 5mm error.
As you suggested, I think the seat shape's a factor - not just the lower section incline (or lack of), but that the lumbar section curve is not so pronounced as I'd guess your hardshell seat is, and certainly not as much as on a Hurricane (I've got one sitting in the workshop sadly mostly ignored in favour of the SPM) - I'd guess Andy's seat would be pretty similar
The ankling bit might be relevant too - I tend to pedal toe down, tho' that's not always the case.
Andy's 2" shift (that's huge !) might indicate there's quite a bit of wiggle-room, mileage and other biomechanical nasties permitting..
